[GUI] file decorator dots are now colored

Also changed the logic. Only the path to the active editor is now
colored and no longer the path to other opened editors.

Change-Id: I42c0b9808968234992c465e6b3377011deb48286
Reviewed-on: http://saros-build.imp.fu-berlin.de/gerrit/1105
Reviewed-by: Franz Zieris <zieris@inf.fu-berlin.de>
Tested-by: Jenkins CI